Newt Gingrich wants to swing into Washington like a wrecking ball and demolish the key barriers between the GOP and the end of universal health care. But his primary target isn’t Obamacare itself. Rather it’s a non-partisan agency most people outside the beltway have never heard of — but that the D.C. establishment would arise and take arms to protect.

“If you are serious about real health reform, you must abolish the Congressional Budget Office because it lies,” Gingrich said at a Saturday debate with embattled pizza entrepreneur Herman Cain. “Every hospital will tell you that if you get the family and patient involved, it is better and less expensive. The Congressional Budget Office refuses to see this as a savings. It wants more bureaucracy and less patient involvement.”

In a technical sense, Gingrich is correct. The Congressional Budget Office will make it hard for Republicans to completely repeal Obamacare, even if they unify control of government in 2013. CBO is the agency that evaluates for lawmakers the impact their legislation is expected to have on the federal budget. And unfortunately for Republicans, the health care law was devised to score as a deficit reducer, particularly after its first 10 years of existence. By direct corollary, the CBO says repealing the whole thing would increase projected deficits. For political and (more importantly) procedural reasons, that would make a complete repeal almost impossible.

Some Republicans want to change the rules that make CBO’s words so powerful. Gingrich, by contrast, wants to get rid of CBO altogether. In response, former CBO heads are leaping to its defense — including a key conservative economist, influential among Republicans.“Obviously I completely disagree,” emails Doug Holtz-Eakin, who directed the CBO for nearly three years when Republicans controlled Congress under President George W. Bush, and now runs the conservative American Action Forum. “Regardless of his view of the merits of CBO’s analyses, it remains the case that it is a strictly advisory body that identifies the budget costs (not the economic costs or social benefits) of policy options. The rest of the benefit-cost analysis and ultimate decision-making likes with Congress. If he is unhappy with legislative outcomes, his fight is with Congress; not the CBO.”

“Congress needs the CBO more now than ever, because policy differences have become so partisan,” Rivlin said in an email. “Each side slants the numbers to favor their outcome. There has to be a neutral nonpartisan scorekeeper. Everybody hates the referee–and no ref gets all the calls right–but the game would be chaos without one.”

CBO has been an obstacle for conservatives in the past. Most famously, their march for large permanent tax cuts during the George W. Bush administration hit a brick wall when CBO, which concluded, correctly, that the cuts would lead to significant budget deficits. Lacking Democratic support, the GOP used special procedural rules to circumvent a filibuster and pass the cuts on a partisan basis. But those same rules also required deficit-financed legislation to expire after 10 years. That’s why Congress got bogged down in a major fight over the cuts late last year and why they’re now set to expire at the end of 2012.

But CBO can be an ally or an enemy to either party depending on the circumstances. In 1994, the CBO dealt President Clinton a major blow when it concluded that payments to and from private “health alliances” should appear on the federal ledger. As a result, the Clinton proposal appeared to make federal spending mushroom scaring off already-squeamish lawmakers who later scotched the plan altogether.